In accordance with the Third Generation Partnership Project 2 (3GPP2) standards, the CDMA2000 1x network and HRPD network are independent from each other, and there is no interface between the two networks except that both of them can be connected to one Packet Data Service Network (PDSN). A terminal (Mobile Station/Access Terminal (MS/AT)) supporting both the CDMA2000 and the HRPD) can only stay in one network at a given time, that is, in the CDMA2000 network or in the HRPD network. In order to monitor the paging message or system message from the network which MS/AT do not stay in, MS/AT has to be scheduled to switch to the network which MS/AT do not stay in, according to the paging cycle of the network which MS/AT do not stay in, to monitor the paging message or system message.
FIG. 1 is a schematic illustrating the network structures of a CDMA2000 and a HRPD. As shown in FIG. 1, the CDMA2000 includes Base Station Subsystem (BSS) 101 covering the cell where MS/AT 100 is, Mobile service Switching Center (MSC) 102 covering the location area where the MS/AT is, and Home Location Register (HLR) 103 storing the location information of MS/AT. A Packet Control Fashion (PCF) is integrated with BSS 101, which is referred to as BSS/PCF 101. BSS/PCF 101 is connected with PDSN 104. The HRPD includes HRPD Access Network (AN) 105 for accessing a packet data service by MS/AT 100. HRPD AN 105 is integrated with a PCF, which is referred to as HRPD AN/PCF 105. HRPD AN/PCF 105 is connected with PDSN 104. The HRPD also includes Authentication Network server Authentication, Authorization, Accounting, (AN AAA) 106 connecting with HRPD AN/PCF 105 for authenticating MS/AT 100. In addition, PDSN includes AAA 107 which connects with PSDN for authenticating MS/AN 100.
At present, there are two schemes for realizing the reception of the voice paging and incoming call number from a CDMA system in a HRPD terminal.
The first scheme is described as follows: if MS/AT is a double-mode terminal having dual receivers, while HRPD is transmitting the packet data, MS/AT monitors the paging channel of CDMA2000 1x and judges whether there is voice paging message for itself or not, if there is, MS/AT responds to the paging of CDMA2000 1x, and sets tip a traffic channel in CDMA2000 1x; otherwise, MS/AT continues the current data service.
The process of MS/AT switching from HRPD to CDMA2000 1x, setting up the traffic channel and receiving the incoming call is as follows: the HRPD network switches MS/AT from the mode of receiving a packet data service to the mode of HRPD Dormant, and then switches the terminal to CDMA2000 1x to respond the paging request and set up a traffic channel; then CDMA2000 network transmits the incoming call number via the established traffic channel, waits for the MS/AT to make a response of whether accepting this incoming call or not. If the user chooses to accept the incoming call CDMA2000 1x network side accepts this call. If the user chooses not to accept the incoming call, CDMA2000 1x switches MS/AT back to HRPD Dormant and re-activates the packet data service for the MS/AT.
The second scheme is described as follows: if the MS/AT which stays in HRPD has a single receiver or a single transmitter, in order to receive the voice paging message of CDMA2000 1x, MS/AT must be periodically switched to CDMA2000 1x in accordance with the paging cycle of CDMA2000 1x, and monitor the voice paging message in the paging channel of CDMA2000 1x. If there is a voice paging message, MS/AT responds to the paging of CDMA2000 1x, and sets up the traffic channel in CDMA2000 1x; CDMA2000 1x transmits the incoming call number to MS/AT so that the user can decide whether to accept the incoming call. If there is no voice paging message or the user decides not to accept the incoming call, the MS/AT switches back to HRPD, and continues the current data service.
In order to prevent an MS/AT from frequently switching between two networks in the second scheme, the function of forwarding CDMA2000 1x messages via HRPD is added to the air interface of HRPD standard network, such as the function of forwarding a paging message, short message and system message. However, the A interface can not support the function, and there is no solution at present. This forwarding function prevents an MS/AT with single receiver or single transmitter from switching frequently between two networks in order to receive a paging message of CDMA2000 1x, that is, MS/AT with single receiver or single transmitter can stay in HRPD, and receive a paging message from CDMA2000 1x network via HRPD.
It can be realized that MS/AT need not frequently search between two networks by adopting double receivers or by forwarding the paging message of 1x network via HRPD network. However, as the incoming call number can not be sent until CDMA2000 1x has set up the traffic channel, even if the user does not intend to accept the incoming call with the incoming call number transmitted via the traffic channel, MS/AT have to switch to CDMA2000 1x first, set up a traffic channel, and then obtain the incoming call number transmitted via the established traffic channel, afterward the user has to determine not to accept to this coming call.
As the switching time between CDMA2000 1x and HRPD is long, those packet data services having a high requirement on real time operation, such as Voice of Internet Protocol (VoIP), Push to Talk (PTT), Video Phone and stream media services, may have been interrupted during the process of switching, which seriously influences the reception and transmission of packet data services for MS/AT.